The present invention relates to cargo pallets of the type used by cargo and freight carrying vehicles; for example, cargo aircraft.
This invention further relates to cargo pallets having, as an integral part thereof, extendable and retractable load bearing roller means to facilitate transportation of pallets within a cargo compartment and movement thereof within the compartment as well as into and out of the compartment.
The transportation of cargo by air is generally accomplished by an aircraft specifically adapted to receive and stow within its cargo hold a plurality of substantially rectangular pallets upon which the cargo is loaded. Such pallets may, but need not necessarily, have vertically extending sidewall portions as a part of their structure. Heretofore, cargo-carrying aircraft embodied within their structures extensive, heavy and complicated equipment and machinery to accommodate both bulk cargo and palletized cargo, and to move such cargo into and out of stowed positions within the cargo holds. Such equipment and machinery typically included drive means, traction means, drive rollers, idler rollers, guide rollers, guides and the like. Accordingly, the initial cost of these extensively equipped aircraft, together with the maintenance and down time, or out-of-service, cost thereof has been substantial. Furthermore, the weight of the built-in equipment and machinery has posed additional disadvantages of "dead" weight when the cargo was volume-limited and reduced net payload when the cargo was weight-limited. In either instance, a cargo-carrying aircraft encumbered by such disadvantages could operate neither as efficiently nor as economically as desired.
Although the idea of incorporating some of the required equipment and machinery within cargo pallets and containers has occurred in the past, it has usually not been implemented for aircraft use because of the structural strength, hence weight, needed in the floors of cargo-carrying aircraft to withstand the concentrated loads imposed by heavy pallet support and suspension systems under the various loads encountered in loading and unloading as well as in flight. The prior art discloses numerous approaches and attempted solutions directed to the aforementioned problems and disadvantages. Broadly, the prior art discloses apparatus intended to simplify, minimize and, where possible, eliminate cargo handling equipment and machinery built into, or carried by, vehicles employed for transportation of cargo and freight. The prior art met these problems and disadvantages with varying degrees of success, but none solved them completely; particularly with respect to aircraft where requirements are somewhat different than those of other vehicles.